Standard diversion boxes are widely used to divert water from watercourses for water supply systems and hydroelectric power generation. Hydroelectric diversion boxes can divert a significant portion of the watercourse flow into a penstock (pipe) through which the water is conveyed to energize a turbine/generator to create electric power. The remaining, and often smaller, portion of the watercourse flow passes over the diversion box and downstream in the watercourse and is referred to as the “bypass flow.” Maintaining an adequate bypass flow is important because when the bypass flow falls below a specified volume, negative environmental impacts result to the riverine ecosystem and its aquatic life.
During periods of reduced natural water flow in a watercourse, such as that which occurs in summer drought periods, in a standard diversion box the bypass flow is reduced because the natural water flow has diminished but the water flow diverted to the penstock by the diversion box remains static. As a result, reduced natural water flow in the stream may reduce the health of the riverine ecosystem.
The present apparatus enhances the functionality of the standard diversion box by ensuring that the bypass flow will meet or exceed a specified volume and thus provide minimum bypass flow levels required to maintain healthy riverine ecosystems. As described herein, the present method and apparatus is designed such that the bypass flow takes precedence over flow diverted for hydropower generation and therefore ensures that minimum bypass flows are maintained to support the health of riverine ecosystems.
There is described herein an apparatus for ensuring a minimum bypass flow installed in a stream, having a diversion chamber having dual parallel side panels extending upwardly from outer edges of a floor panel and front and rear panels of varying height, a tilted wire wedge wire screen inclining downwardly and mounted between the side panels and the front and rear panels, a bypass chamber mounted within the diversion chamber having a bypass inlet and a bypass outlet, and a secondary chamber mounted within the diversion chamber and including an outlet port. The bypass chamber being defined by isolation walls, and the second outlet chamber mounted within the diversion box having second isolation walls with an open upper end and a penstock port, the second isolation walls being higher than the bypass inlet so that water flows into the second chamber only when the water level is above the second isolation walls. There is also provided a method of ensuring minimum bypass flow levels in a stream.